The sequence provided is:

$-1, -6, -11, -16, -21$

This is an arithmetic sequence because the difference between consecutive terms is constant. Let's find the common difference ($d$):

$d = -6 - (-1) = -6 + 1 = -5$

The first term ($a$) is $-1$, and the common difference ($d$) is $-5$.

The general formula for the $n$th term of an arithmetic sequence is:

$a_n = a + (n - 1) \cdot d$

Substitute the values of $a = -1$ and $d = -5$:

$a_n = -1 + (n - 1) \cdot (-5)$

Simplify the expression:

$a_n = -1 - 5(n - 1)$ $a_n = -1 - 5n + 5$ $a_n = 4 - 5n$

Thus, the $n$th term of the sequence is:

$a_n = 4 - 5n$

Do you want further details or have any questions?

Here are 5 related questions to expand your understanding:

1. How do you find the common difference in any arithmetic sequence?
2. Can you derive the $n$th term for a sequence where the common difference is positive?
3. What is the sum of the first $n$ terms of an arithmetic sequence?
4. How can we determine whether a given sequence is arithmetic or geometric?
5. What changes in the formula if the sequence starts with a positive first term?

Tip: In arithmetic sequences, always check the difference between terms to identify patterns.